New Delhi, Jan 6 (IANS) School-based immunisation against human papillomavirus (HPV) could also offer protection against the development of pre-cancerous cells in unvaccinated women through herd immunity, according to a paper published in The Lancet Public Health journal on Tuesday.

HPV is a common sexually transmitted infection and the main cause of cervical cancer.

HPV vaccination is known to greatly reduce the risk of serious cervical changes in people who are vaccinated, but it has been less clear whether it also protects those who are not vaccinated.

“School-based HPV vaccination programmes play an important role as a cost-effective strategy to reduce cervical disease and cancer risk not only in vaccinated individuals, but across entire populations,” said Eva Meglic, from the Karolinska Institutet.

“This finding shows that the herd effect can be achieved through high-coverage HPV vaccination,” added the researcher.

The study analysed Swedish national health registry data from over 800,000 unvaccinated women born between 1985 and 2000.

The study compared rates of pre-cancerous changes in the cervix across birth cohorts exposed to different HPV vaccination strategies in Sweden: opportunistic vaccination (1985-1988), subsidised programmes (1989-1992), catch-up programmes (1993-1998), and school-based vaccination (1999-2000).

The study found that unvaccinated women born in 1999 and 2000 in Sweden, who grew up alongside peers vaccinated through a school-based programme, had about half the risk of developing serious precancerous changes in the cervix compared with unvaccinated women born between 1985 and 1988, when vaccination uptake was lower and only given to women who sought it out.

However, the team noted that as an observational study, the findings may be affected by other factors, such as differences between birth cohorts in sexual behaviour, cervical screening participation, testing practices, and access to healthcare.

Yet, from a policy and implementation perspective, these results advocate for sustained efforts in universal vaccination initiatives, particularly those targeting school-aged populations, to maximise the benefits, the researchers said.

–IANS

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